From 4c098dab121a4164e9daa4d1ddbc59e93054e79e Mon Sep 17 00:00:00 2001
From: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Date: Mon, 26 Aug 2019 22:54:15 +0900
Subject: [PATCH] ALSA: oxfw: fix NULL pointer dereference to unused stream structure
Git-commit: 4c098dab121a4164e9daa4d1ddbc59e93054e79e
Patch-mainline: v5.4-rc1
References: jsc#SLE-16518

ALSA oxfw driver supports Griffin FireWave. This device supports one
isochronous stream for PCM playback. Current driver executes code to
wait event for stream structure of opposite direction. This causes
NULL pointer dereference.

This commit fixes the bug.

Fixes: ac5d77864cfc ("ALSA: oxfw: support AMDTP domain")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 sound/firewire/oxfw/oxfw-stream.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/sound/firewire/oxfw/oxfw-stream.c b/sound/firewire/oxfw/oxfw-stream.c
index 0318dc4dcc55..3c9a796b6526 100644
--- a/sound/firewire/oxfw/oxfw-stream.c
+++ b/sound/firewire/oxfw/oxfw-stream.c
@@ -350,13 +350,18 @@ int snd_oxfw_stream_start_duplex(struct snd_oxfw *oxfw)
 
 		// Wait first packet.
 		if (!amdtp_stream_wait_callback(&oxfw->rx_stream,
-						CALLBACK_TIMEOUT) ||
-		    !amdtp_stream_wait_callback(&oxfw->tx_stream,
 						CALLBACK_TIMEOUT)) {
 			err = -ETIMEDOUT;
 			goto error;
 		}
 
+		if (oxfw->has_output) {
+			if (!amdtp_stream_wait_callback(&oxfw->tx_stream,
+							CALLBACK_TIMEOUT)) {
+				err = -ETIMEDOUT;
+				goto error;
+			}
+		}
 	}
 
 	return 0;
-- 
2.16.4